Iraq's interior minister has offered to resign, part of the political fallout from Sunday's devastating attack in Baghdad.

Mohammed Ghabban on Tuesday handed over authority to his deputy until the offer is considered by Prime Minister Haider al-Abadi, himself the target of public rage after a suicide truck bombing killed at least 175 people.

Rescuers are still going through the blast site in the Karrada district looking for people who are missing in one of the deadliest attacks to hit the capital since the U.S. invasion in 2003.

Islamic State militants claimed responsibility for the bombing, saying they were targeting Shi'ites.

The attack came near the end of the Muslim holy month of Ramadan, a time when U.N. envoy for Iraq Jan Kubis had hoped there would be a lull in violence.

"The terrorists did not spare an occasion to strike at markets, mosques and areas where people gathered in order to exact maximum casualties among civilians, despite the religious occasion and in total disregard for the values of Islam," Kubis said.

In Washington, U.S. State Department spokesman John Kirby said Tuesday that a military campaign is not enough to defeat the Islamic State terrorist group, adding "a holistic campaign that addresses the root causes of extremism is the only way to deliver a sustainable defeat."

Iraqis grieve during the funeral procession of bomb victim, Akram Hadi, 24, who was killed in a massive truck bomb attack in the Karada neighborhood of Baghdad, Iraq, July 5, 2016.

The U.S. is working closely with partners from around the world to cut off the messaging, financing and recruitment networks of Islamic State. "The United States now has information-sharing agreements with 55 international partners to identify and track the travel of suspected terrorists," Kirby said.

U.N. Human Rights High Commissioner Zeid Ra’ad Al Hussein also deplored the loss of innocent lives and condemned what he called this latest "horrendous atrocity" by the extremist Sunni group Islamic State.

Call to reign in militias

But responding to reports of increased attacks by pro-government Shi'ite militias on Sunni civilians, Al Hussein Tuesday also called on the Iraqi government to reign in uncontrolled militia who are continuing to take revenge on civilians fleeing towns recaptured from IS.

Zeid is urging the government to immediately relocate and free more than 600 men and boys reportedly abducted by a militia group involved in the recapture of Fallujah from IS in June.

The high commissioner’s spokesman, Rupert Colville, says fighters from the Kata'ib Hezbollah militia immediately separated men and teenage boys from the women and children, who were transferred to government-run camps for displaced people. He says mistreatment began almost immediately.

“Men were crammed into small rooms or halls, sometimes more than 60 to a room," Colville said. "[A] number of witnesses attested that some who asked for water or who complained about the air were dragged outside and shot, strangled or severely beaten. In addition, witnesses stated that at least four men were beheaded.”

Iraqi women grieve as people light candles at the scene of a massive car bomb attack in Karada, a busy shopping district where people were shopping for the upcoming Eid al-Fitr holiday, in the center of Baghdad, Iraq, Monday, July 4, 2016.

No more atrocities

High Commissioner Zeid acknowledges Iraq needs fighters in its ongoing battles with IS; but, he urges authorities to take serious action to prevent militias allied to the government from carrying out further atrocities. He adds those perpetrating crimes must be held to account.

With the cycle of violence persisting, Prime Minister Abadi got an angry reception Sunday when he visited the area of the truck bombing, with some people throwing stones and other objects to express their contempt. He ordered tighter security measures in Baghdad.

Colville says such acts of revenge are helping IS carry out its strategy to divide societies and promote hatred. He says revenge attacks are counterproductive, breed resentments and are a great propaganda and recruitment tool for Islamic State, also known as ISIL.

A girl walks past the site after a suicide car bomb attack at the shopping area of Karrada, a largely Shi'ite district, in Baghdad, Iraq, July 4, 2016.

Terrorists executed

The government also announced Monday the execution of five convicted terrorists and said authorities had arrested 40 people suspected of planning more attacks.

Colville says such acts of revenge are helping IS carry out its strategy to divide societies and promote hatred. He says revenge attacks are counterproductive, breed resentments and are a great propaganda and recruitment tool for Islamic State.